JP2716631B2 - Light head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head for irradiating a light spot on an information recording medium such as an optical disk to optically read or write information.

[0002]

2. Description of the Related Art FIG. 4 is a layout diagram showing a configuration of an optical system of a conventional general optical head disclosed in Japanese Patent Application Laid-Open No. 3-241532. In the figure, a semiconductor laser 1 irradiates a laser beam to a half mirror 2 and gives the reflected light to an optical disk 4 via an objective lens 3. Then, the reflected light from the optical disk 4 is transmitted through the objective lens 3 to the half mirror 2.
The optical signal transmitted through the half mirror 2 is guided to the photodetector 6 via the concave lens 5. Here the semiconductor laser
The laser detector 1 and the photodetector 6 are in a conjugate positional relationship with respect to the half mirror 2. The position is adjusted by moving along the light receiving surface. After the position of the light detector 6 is adjusted, the light detector 6 is fixed to the optical housing. FIG. 5 shows a printed circuit board 7 on which the photodetector 6 is mounted. After being attached to the printed circuit board 7, it is attached to the optical housing 8 as shown in FIG. The metal plate 9 lined with the printed circuit board 7 is fixed to the optical housing 8 by laser welding 10. In addition, as shown in FIG.
Some are fixed by 1.

[0003]

As described above, conventionally, the position of the photodetector for appropriately obtaining signals such as a focus error signal for focus servo and a tracking error signal for tracking servo is used. After the adjustment, the metal plate on which the photodetector and the printed circuit board are mounted is directly fixed to the optical housing by laser welding or bonding. Therefore, there has been a problem that a positional deviation such as a position adjustment failure of the photodetector occurs, and if this is found in the final test, it is difficult to readjust the position. Because it is very difficult to remove the weld
There are, also is working so very time-consuming to completely remove the adhesive. If these operations are not possible, the optical housing on which expensive optical components such as LDs and prisms are attached must be discarded, resulting in a large loss. The present invention has been made in order to solve such a problem, and when the position adjustment and fixation of the photodetector are completed, if re-adjustment is required due to a position shift such as position adjustment failure, the present invention is easily performed. An optical head capable of removing a photodetector from an optical housing is provided, and the optical housing can be reused.

[0004]

An optical head according to a first aspect of the present invention is fixed on an optical housing by adjusting its position.
That an optical detector, a first substrate, on which the photodetector is mounted, a second substrate, on which the first substrate is mounted, for fixing the second substrate to the optical housing
Has a screw and fixes the second substrate to the optical housing
Adjustment of the photodetector integrated with the first substrate in the state
After it has been made, in which the above-described first substrate and the second substrate were so Ru is fixed by welding.

An optical head according to claim 2 of the present invention.
It includes a photodetector which is fixed to the position adjustment on the optical housing, and the substrate where the light detector is mounted, the substrate
And a screw for fixing the
After being Gana position adjustment of the optical detector the substrate in a fixed state to the optical housing, in which the optical detector and the said substrate has a so that fixed by welding.

[0006]

In the optical head according to the first aspect of the present invention,
After the end of the position adjustment of the optical detector, the first substrate where the light detector is mounted is, the second substrate attached with screws to the optical housing and secured two welding. Further, since the second substrate is fixed to the optical housing by the screw, the photodetector can be easily removed from the optical housing by removing the screw.

Further, according to a second aspect of the present invention, there is provided an optical head.
Oite, after positional adjustment of the photodetector is finished, the optical detector, the board mounted with screws to the optical housing, soluble
It is to be fixed by two contact.

[0008]

【Example】

Embodiment 1 FIG. FIG. 1 is a perspective view showing an optical head according to an embodiment of the present invention. In the figure, the same parts as those in the above-described conventional example are denoted by the same reference numerals. The light detector 6 is mounted on a printed circuit board 7, which is fixed to a first board 12 in advance. Reference numeral 13 denotes a second substrate, which is previously provided with an optical housing 8 by screws 14.
It is fixed to. The first substrate 12 and the second substrate 13 are fixed by welding after adjusting the position of the photodetector 6. Reference numeral 10 denotes a welded portion, and the first substrate 1
2, the second substrate 13 is made of a material that can be welded.

Next, the position adjustment operation of the photodetector 6, that is, the position adjustment operation of the block in which the first substrate 12, the printed circuit board 7, and the photodetector 6 are integrated will be described. In the case of a general optical head, for example, the conventional example shown in FIG. 4, the photodetector 6 not only has a function of receiving reflected light from the optical disk 4 and reading information signals recorded on the optical disk 4, but also a function of reading the optical signal. Focus error signal for focus servo to make the laser beam emitted from the objective lens 3 always focus on the optical disk with respect to the surface deflection caused by the rotation of the optical disk 4, and the information track or the guide groove on the optical disk 4 (FIG. (Not shown), an optical head is configured so as to obtain a tracking error signal for tracking servo for correctly following the converged spot of the irradiation laser beam from the objective lens 3, and the photodetector 6 is adjusted with strict positional accuracy. Is done. Here, consider the case where the photodetector 6 in FIG. 4 is a photodetector for obtaining a focus error signal by an astigmatic focus sensor.

[0010] receiving surface 20 of the optical detector 6 in FIG. 8, a proper light spot on及beauty optical <br/> disc 4 is irradiated, and on the light receiving surface 20 of the photodetector 6 which are position adjustment Illuminated light spot 21 is shown. The light receiving surface 20 is a divided light receiving surface 2
0a, 20b, 20c, and 20d. Sa ~
Sd is a signal from each light receiving surface, and the focus error signal FE is obtained by the calculation of FE = (Sa + Sc)-(Sb + Sd). The size of the light spot on the light receiving surface 20 is arbitrary depending on the design of the optical head optical system, but is usually about 50 to 100 μm. Therefore, even if the photodetector 6 is displaced by about 10 μm from the correct adjustment position, an appropriate focus error signal cannot be obtained.
For this reason, after the position adjustment, the light detector 6 is moved to the optical housing 8.
When the screw is used, the position adjustment jig of the light detector 6 is removed after the position adjustment for correcting the position shift of the light detector 6 due to the tightening of the screw when the screw is used. lever to put the misalignment stress is applied, necessary to perform the readjustment of the optical detector 6 is arising. However, when the photodetector 6 is fixed to the optical housing 8 only by welding, there is no positional deviation due to the above factors, and high arrangement accuracy can be maintained.

However, when the photodetector 6 is fixed by the method shown in the conventional example, the position of the photodetector 6 is not adjusted properly, or the optical components constituting the optical head optical system and the holders for fixing the optical components are used. When a positional shift due to a change in environmental conditions such as aging positional shift and temperature and humidity occurs, it is difficult to remove the photodetector, which is difficult if the position is fixed only by welding, to the second substrate 13 by the optical housing 8.
It can be easily performed by removing the screw 14 fixed to the. The first substrate 12 and the second substrate 13 are made of a metal plate such as aluminum, but other materials may be used as long as they can be welded. Further, the first substrate 12 and the second substrate 13 are fixed by welding, but as shown in FIG.
May be fixed.

Embodiment 2 FIG. In the first embodiment, the entirety of the light detector 6 fixed to the first substrate 12 via the printed circuit board 7 is adjusted in position and fixed to the second substrate 13 by welding or bonding, as shown in FIG. Alternatively, the photodetector 6 may be directly fixed to the second substrate 13 by welding or bonding without using the first substrate 12. Although the printed circuit board 7 is not shown in FIG. 3, the printed circuit board 7 may be attached after the photodetector 6 is fixed, and may have any shape as long as the structure does not hinder the welding or bonding of the photodetector 6. It is.

[0013]

As evident from the foregoing description, according to the present invention, after the photodetector to adjust the position, since the fixed more optical housing welding, can be kept high positional accuracy during photodetector mounted . In the method of fixing a more direct light detector to welding to the optical housing, removal of the photodetector in the case where the re-adjustment by the position adjustment failure or the like of the optical detector becomes necessary was difficult after fixation. However, in claim 1 of the present invention, the second substrate is previously mounted on the optical housing by screws between the first substrate on which the photodetector is mounted and the optical housing. Even if the need for readjustment due to poor adjustment or the like is found after fixing the photodetector, the second substrate can be easily removed from the optical housing with screws. According to a second aspect of the present invention, an optical housing is provided.
The photodetector is fixed to the board
Position can be adjusted with high accuracy
Easy re-adjustment due to poor position adjustment of the detector
Can be removed. Therefore, optical parts such as expensive LDs and prisms
Can be reused .

[Brief description of the drawings]

FIG. 1 is a perspective view showing an optical head according to an embodiment of the present invention.

FIG. 2 is a diagram showing a state in which the substrate in FIG. 1 is fixed with an adhesive.

FIG. 3 is a perspective view showing an optical head according to another embodiment of the present invention.

FIG. 4 is a layout diagram showing a configuration of an optical system of a conventional general optical head.

FIG. 5 is a diagram showing a configuration of a conventional photodetector and a printed circuit board.

FIG. 6 is a configuration diagram of a conventional photodetector mounting portion.

FIG. 7 is a configuration diagram of another conventional photodetector mounting portion.

FIG. 8 is an explanatory diagram showing a light receiving surface and a light spot of a photodetector.

[Explanation of symbols]

 Reference Signs List 6 light detector 8 optical housing 10 welded part 11 adhesive 12 first substrate 13 second substrate 14 screw

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Morihiro Karaki 1 Baba Zujo, Nagaokakyo-shi, Kyoto Mitsubishi Electric Corporation, Electronic Products Development Laboratory (72) Hideaki Kobachi 1 Baba Zhou, Nagaokakyo-shi, Kyoto Mitsubishi (56) References JP-A-4-10223 (JP, A) JP-A-4-113525 (JP, A)

Claims (2)

(57) [Claims] 1. The optical system according to claim 1 , wherein the position is adjusted and fixed on the optical housing.
An optical detector that includes a first substrate, on which the photodetector is mounted, a second substrate, on which the first substrate is mounted, for fixing the second substrate to the optical housing
And fixing the second substrate to the optical housing.
Position of the photodetector integrated with the first substrate in a fixed state
After settling has been made, the optical head and the first substrate and the second substrate is characterized by a Turkey are fixed by welding. 2. The optical system according to claim 1 , wherein the position is adjusted and fixed on the optical housing.
A photodetector, a substrate to which the photodetector is attached, and a screw for fixing the substrate to the optical housing, wherein the substrate is fixed to the optical housing . after being alignment Gana, the optical head the optical detector and the said substrate, characterized in Rukoto fixed by welding.